This project proposes to contribute to the understanding of the structure and function of oncornavirus RNAs. For the studies we will use as a model virus B77 avian sarcoma virus. The objectives of this research are: 1. To determine the significance of methylation of viral genome RNA and mRNAs and its possible role in oncornavirus replication by: (a) testing the effect of in vivo inhibitors of RNA methylation; (b) testing the biological and enzymatic activities of undermethylated virus; (c) determining the role of the host cell and virus in specifying the sites and extent of methylation. 2. To isolate and characterize viral specific mRNA from infected cells and to determine their relationship to viral genome RNA. 3. To determine whether viral polypeptide p19 and/or its phosphorylated derivative are bound to viral RNA in the infected cell.